Root Causes of Complexity in iOS apps

Software complexity is a real problem that is causing lots of monetary losses in enterprise software systems around the world. As iOS apps are getting bigger, they may start to suffer the effects of complexity (more bugs, ineffective testing...). In this talk we are going to explore how using more restrictive models than object oriented programming can help us manage this complexity, with the trade offs of producing less natural solutions, and an impact on modularity. The main topics will be:

- The importance of understanding our programs
- Kinds of complexity in iOS apps
- Effects of state in our understanding of programs, and in testing
- How Swift help us model a functional core
- Testing our functional core using property based testing
- Redux implementations in iOS

Transcript

1. ROOT CAUSES OF COMPLEXITY IN IOS APPS
2. THE IMPORTANCE OF UNDERSTANDING PROGRAMS YOU CANNOT EXTEND A PROGRAM SUCCESSFULLY IF YOU DON’T UNDERSTAND IT
3. WHAT’S COMPLEXITY? ▸ Intrinsic complexity: Caused by the problem domain. ▸ Accidental complexity: Caused by our translation of solutions to problems using a particular language. Most complexity in iOS apps is of this kind
4. STATE
5. MAKE STATE A FIRST CLASS CITIZEN ReSwift (https://github.com/ReSwift/ReSwift)
6. THE EXPRESSION PROBLEM count first New Operations Array Set New Types OOP FP
7. ALGEBRAIC TYPES FOR THE DOMAIN MODEL Sum types (Enums) Product types (Tuples and Structs)
8. THE POWER OF LENSES ▸ Updating algebraic data types can be cumbersome. ▸ Functional languages use the concept of lenses.
9. THE POWER OF LENSES
10. HOW DO WE TEST THIS? ▸ Property based testing library (https://github.com/typelift/ SwiftCheck), inspired by Haskell’s QuickCheck and Scala’s ScalaCheck.
11. WANT MORE PROPERTY BASED TESTING FOR IOS? ▸ Do this Kata by the people from Karumi: https:// github.com/Karumi/MaxibonKataIOS
12. CONCLUSIONS ▸ You cannot extend a program you don’t understand. ▸ Mix of ortogonal concepts like inheritance and polymorphism are being solved by modern languages like Swift. ▸ Libraries like ReSwift help with complexity caused by state and encourages separation between side effects and pureness. Still a work in progress. ▸ Use the most restrictive programming model for the problem, in which the solution is natural (ie. not fighting against the framework).
13. THANKS Daniel Martín @dmartincy